In recent years energy consumption has become a critical issue for mobile telecommunication networks. Telecommunication networks are continuously evolving for instance with the deployment of third generation (3G), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), LTE and LTE-A mobile telecommunication equipment. As a consequence a huge amount of energy is needed in order to operate all this radio equipment.
In the past main interest in research and standardization has been given to develop telecommunication equipment and digital radio transmission schemes that ensure higher spectral efficiencies and a better quality of service (QoS). Energy consumption has not been considered as a constraint so far. However with the currently started discussion in 3GPP and the consideration of study and work items focusing on network power saving this paradigm is likely to change.
According to recent discussions in 3GPP there should be defined solutions for energy saving from the perspective of radio access for the LTE-A network or E-UTRAN (Evolved Universal Terrestrial Radio Access Network). Within the framework of 3GPP currently the following principles should be followed when developing solutions for energy saving in LTE-A or E-UTRAN: (a) Energy saving solutions should be justified by valid radio scenario(s) and should be based on the actual load situation within the network and/or within the respective network cell which is considered for energy saving measures. (b) The accessibility of users respectively user equipments (UEs) should be guaranteed when a cell transfers to an energy saving mode. (c) Backward compatibility should be ensured. Specifically, the ability to provide energy savings for LTE release 10 system deployments should be ensured, which support a number of earlier release UEs.
Further, new energy saving mechanism should support the following load-dependent adaptation aspects: (a) It should be possible to switch on/off a particular Base Station (BS) respectively cell based on a monitoring of radio data traffic within the cell. (b) It should be further possible to perform a semi-static reconfiguration of transmission antenna numbers of a BS such as an evolved NodeB (eNB). This means that depending on the radio traffic and/or on the quality of radio connections between the BS and one or more UEs, one or more antennas together with the respective power amplifier can be switched on/off. In this respect semi-static means that the typical time scale for switching is in the order of one or more seconds. (c) Furthermore, in order to save energy it should be possible to perform a semi-static reconfiguration of the bandwidth for a control channel and a signal comprising a Common Reference Symbol (CRS). Again, semi-static means that the typical reconfiguration time is in the order of one or more seconds.
WO2009/140988A1 discloses a method for reducing a power consumption of a base station of a radio telecommunication network in a low load scenario. Specifically, within a sector of the telecommunication network the network can turn off entire transmitter chains comprising one or more base stations, whereas the respective receiver chains remain activated. This capability can be broadcasted together with a respective lifetime information defining the validity of the broadcasted message. In order to wake up base station downlink transmitters, a specific message transmitted on the Random Access Channel (RACH) is used, wherein this message comprises specific assigned preamble sequences.
Due to the continuous development of mobile telecommunication technology and the deployment of the corresponding mobile telecommunication equipment it is frequently the case that different Random Access Technology (RAT) communication devices are deployed in parallel. In this respect “deployment in parallel” means that within one and the same region different Random Access Technology (RAT) communication devices are available. Such a multi RAT deployment might be given for instance in regions where, even though there is already LTE or LTE-A radio access provided by new respectively non legacy base stations (BSs), there is still Global System for Mobile Communications (GSM) equipment in operation such as in particular GSM BSs in operation, which exclusively serve old respectively legacy UEs.
There may be a need for providing effective energy saving measures, which take benefit from the fact that within a specific region different RAT equipment is deployed.